Loft conversions in Oxford

One builder for your loft, from drawings to handover

A loft conversion, or attic conversion, turns dead roof space into a bedroom, an office, or a bedroom with its own en-suite. It’s often the cheapest way to add a room, and you don’t lose any garden.

We take on the whole job. We arrange the drawings and structural calculations, deal with planning or a Lawful Development Certificate, serve the party wall notices and run building control, and then we build it. Both our directors, Henry and John Lynch, started out as carpenters, and one of them is on site on every live job. J & H Lynch plaster the walls and Noble Painting & Decorating finish them. Both are Lynch Group companies.

Recent lofts include Boulter Street in St Clement’s, Oxford, and Faringdon Road in Abingdon.

The four types of loft conversion

Rooflight (Velux) conversion

We fit windows into the existing roof slope and leave the roof shape alone. It’s the simplest and cheapest option, but it only works if the loft already has good headroom.

Rear dormer

A dormer is a box-shaped extension built out from the rear roof slope. It gives you vertical walls and full headroom across much of the room, and it’s the most common choice for Oxford’s terraces and semis.

Hip-to-gable

Where a house has a sloping side roof, we build the side wall up into a vertical gable, which makes the loft much bigger. On semis and detached houses we often combine it with a rear dormer.

Mansard

A mansard replaces the rear roof slope with an almost vertical wall and a flat top. It gives the most space of the four, usually needs a planning application, and is common where the existing headroom is low.

What a loft conversion costs in Oxford in 2026

These ranges match our 2026 loft conversion cost guide, which goes into full detail. Professional fees, party wall surveyors and any planning fee come on top.

The type of roof, the stairs and the amount of steel decide most of the price. We price every loft from a survey, with a written, itemised quote.

Will your loft convert?

Most lofts can be converted. Three things decide how easily.

Headroom. As a rule of thumb, you need about 2.2 metres between the ceiling joists and the underside of the ridge. Less than that usually means a mansard, raising the roof or lowering the ceilings below, and each of those adds cost.

Roof structure. Older houses often have a traditional cut roof with open space inside. Many houses built since the 1960s have trussed rafters, with timbers running across the whole loft. Trusses can be converted, but they need new steel beams, so the job costs more.

Space for the stairs. The new stairs usually go above the existing ones. Building regulations ask for 2 metres of headroom over a staircase, but in a loft conversion 1.9 metres at the centre and 1.8 metres at the side is acceptable. We plan this on the first visit, because it shapes the layout of both floors.

Loft conversion planning permission and applications

Most loft conversions on houses are permitted development, so they don’t need a planning application. The main limits are in the table below.

You’ll need a planning application in a conservation area or an Area of Outstanding Natural Beauty, such as the Chilterns or the Cotswolds, and for a flat or a loft bigger than the limits above. The same goes where an Article 4 direction has removed permitted development rights. Listed buildings need listed building consent.

Lawful Development Certificate

Even when a loft is permitted development, we recommend getting a Lawful Development Certificate from the council. It proves the work is lawful, and a buyer’s solicitor will ask for it when you come to sell. In 2026 it costs half the planning fee.

When you need a planning application

We prepare the drawings and submit the application for you. In 2026 the council fee for a householder application in England is £548, and councils aim to decide within 8 weeks. Our guides to permitted development and planning permission in Oxfordshire go into more detail.

Building regulations and party walls

Every loft conversion needs building regulations approval, even when it doesn’t need planning permission. Building control checks four main things: the new floor has to carry the load, often with new steel beams; the stairs have to meet the rules above; the escape route down from the loft has to be protected from fire, with fire-resisting doors and linked, mains-powered smoke alarms on every floor; and the roof has to be insulated to current standards.

At the end you get a completion certificate. Keep it safe, because you’ll need it when you sell.

In a semi or a terrace, the Party Wall etc. Act 1996 usually applies, because the new steels sit in the wall you share with next door. You have to give your neighbours notice at least two months before that work starts. We prepare the notices and build the time for them into the programme.

How a loft conversion runs

Survey and design. We check the roof, the headroom and the stairs, then agree a layout. An architect and a structural engineer produce the drawings and calculations.

Approvals. We apply for planning or a Lawful Development Certificate, submit the building regulations application and serve the party wall notices.

Scaffold and structure. Most of the work happens from the scaffold, outside the house. We fit the steels and the new floor, then build the dormer or gable.

First fix. The cables, pipes and heating go in.

Insulation and plaster. We insulate the roof and walls, and J & H Lynch plaster them.

Stairs. We usually open up the stairwell late in the job, so the rooms below stay clean for as long as possible.

Finish and sign-off. We fit the doors, joinery and bathroom, Noble decorate, and building control issues the completion certificate.

On site, a rooflight conversion usually takes 6 to 8 weeks and a dormer 8 to 12 weeks, with a mansard taking longer. Design, calculations and any planning come before that.

Where we convert lofts

Our loft teams work across Oxford and the towns around it, such as Abingdon, Bicester, Carterton, Didcot, Henley-on-Thames, Kidlington, Thame, Wantage and Witney. The full list is on our Oxfordshire areas page. If you’re thinking about more space downstairs as well, see our house extensions and garage conversions pages.

Common questions about loft conversions

How much does it cost to convert a loft in Oxford?

Rooflight (Velux) lofts cost about £25,000 to £45,000 in 2026. Rear dormers run from £45,000 to £75,000, hip-to-gable conversions from £50,000 to £80,000, and mansards from £65,000 upwards. An en-suite adds £8,000 to £15,000, and fees and any planning costs come on top.

What type of loft cannot be converted?

Very few lofts can’t be converted at all, but some cost a lot more. The main problem is low headroom, meaning less than about 2.2 metres from the ceiling joists to the ridge. A very shallow roof pitch, trussed rafters or nowhere to put the stairs also make the job harder, and some houses in conservation areas can’t get permission for a dormer.

Is a loft conversion worth the money?

Usually, yes, if it adds a bedroom. A good loft conversion typically adds 10% to 20% to the value of a house, and Nationwide’s 2025 research found it can add up to 24% when it adds a double bedroom and a bathroom. That’s often more than the work costs, and you get the space without moving house or losing garden.

What are the disadvantages of loft conversions?

You lose the loft as storage, and the new stairs take some space from the floor below. The work needs building regulations approval and often party wall notices, and some roofs need expensive structural work. Without good insulation and ventilation, a loft room can also get hot in summer.

What is the 10 year rule for loft conversions?

It’s a planning rule. If a loft was built without the permission it needed, the council can usually take enforcement action for 10 years; for work finished before 25 April 2024, the old limit was 4 years. Building control can also act on unapproved work for up to 10 years. Planning immunity doesn’t make a loft safe or approved.

Can you sell a house with a loft conversion without planning permission?

Yes, but it can slow the sale down. A buyer’s solicitor will ask for the planning permission or Lawful Development Certificate, and the building regulations completion certificate. If they’re missing, the options are a retrospective application, a regularisation certificate from building control, or indemnity insurance. Each has its limits, so it’s better to get the paperwork right from the start.

How long does a loft conversion take?

A rooflight conversion usually takes 6 to 8 weeks on site and a dormer 8 to 12 weeks, with a mansard taking longer. Allow extra time before work starts for drawings, calculations, planning and party wall notices.

Talk to us about your loft

To arrange a survey, ring 01865 420063 or send us a message through the contact page. Tell us the type of house and roof, and we can say which conversion is likely to fit.